Single‐ and Double‐Layer Bioadsorptive Membranes for Phenol and Methylene Blue Removal From Synthetic Water

ABSTRACT The removal of phenolic pollutants and synthetic dyes from wastewater remains an important environmental challenge due to their potential adverse effects. In this study, single‐ and double‐layer adsorptive composite membranes based on cellulose acetate (CA) and polyvinylpyrrolidone (PVP) are developed by solvent evaporation‐induced phase separation (EIPS). Commercial powdered activated carbon (PAC) and two untreated agro‐waste bioadsorbents, almond shells (Ash) and date pits (Dp), are incorporated either within the polymer matrix or deposited on the membrane surface. The influence of adsorbent nature and location on phenol and methylene blue removal is investigated. The double‐layer membrane D.L(INS(PAC), SRF(Ash)) exhibits the highest methylene blue removal (60%) in both single‐ and mixed‐pollutant systems, while its Ash‐containing surface layer reaches 70% removal when tested separately. In comparison, D.L(INS(PAC), SRF(Dp)) achieves approximately 50%, whereas membranes with Ash or Dp incorporated internally and PAC deposited on the surface show less than 30% removal. Phenol removal remains limited (20%–30%) for all membranes. FTIR analysis confirms interactions between CA and the adsorbents, while contact angles of 47.7°–55° indicate hydrophilic surfaces. The results highlight the importance of adsorbent positioning for methylene blue removal.